Table showing target and actual water use, dam levels, streamflow and rainfall
Target Actual
May water use to date 15.7 billion litres
16.3 billion litres
Dam storage levels N/A 42.3%
Monthly streamflow into dams N/A 0.68 billion litres
May rainfall to date 116.9mm (May average rainfall 1876-2016) 51.6mm
Note: 1 billion litres = approximately 400 Olympic swimming pools. Please note the figures in this table are rounded (except for rainfall) to the nearest whole number.

Water use

Average water use over the past week was 755 million litres per day – above the demand forecast of 729 million litres per day.

Daily water use for the last 5 days

Table showing daily water use for the last 5 days
Date Actual water use (million litres) Forecast water use (million litres)
21/05/2021 780 720
20/05/2021 774 720
19/05/2021 744 720
18/05/2021 740 720
17/05/2021 807 740
Note, water use is calculated up to 8am each day for the previous 24 hour period.

Since 1 July 2020, we have used 267.73 billion litres of water – which is 0.60 billion litres below the forecast target for this period.

Dam levels (total for 15 dams)

The dam storage levels are slightly down on last week and are sitting at a combined 42.3 per cent* of full capacity.

*Please note some dams are filled from different sources - dam levels include the transfer of groundwater and desalinated seawater from treatment plants as well as streamflow (that comes from rainfall). As we use many different sources of water, dams are no longer an accurate indicator of the health of Perth's overall water supply situation.

Streamflow (total for 15 dams)

From 1 May 2021, the dams have received 0.7 billion litres of streamflow. The post-1975 average for the May to April period (called the streamflow year) is 175.63 billion litres.

Sprinkler roster compliance

Since 1 January 2021, we have taken a total of 2,059 actions (warnings + fines) compared with 2,399 actions for the same period in 2020.

Annual rainfall

Perth has received 171.6mm of rainfall since 1 January 2021. The average (1994-2019) rainfall for the same period to the end of May is 173.5mm.

General water news

Water Corporation HQ was buzzing with excitement on Friday as students from seven high schools in Perth, the South West and Great Southern gathered for the 2021 WA Schools Think Tank Challenge final.


Hosted by Water Corporation and the Innovation Institute, the Challenge asked students to design new ways to help inspire people to remain waterwise in the face of climate change and reduced rainfall.


Students also learnt about how traditional owners have been the custodians of WA's water systems for more than 60,000 years.


Water Minister Dave Kelly and Water Corporation CEO Pat Donovan were on hand to congratulate each school for making the final, after four heat events involving more than 23 schools and 180 students.


Ultimately, it was the team from Fremantle College who were crowned winners for their innovative idea for a sink tap and outdoor hose that restricts water flow according to use.


On behalf of everyone at Water Corporation, congratulations to Fremantle College and to every student who took part in this year’s event. We look forward to welcoming you back in 2022!